1. Field of the Invention
The present invention relates to a clutch mechanism of a coat film transfer tool, and a coat film transfer tool comprising this clutch mechanism, and more particularly to a clutch technology for synchronizing the feed speed and take-up speed of coat film transfer tape in a feed reel and a take-up reel, in a coat film transfer tool for transferring a coat film such as corrective paint layer, adhesive layer or the like on a coat film transfer tape onto a sheet of paper or the like, and automatically collecting the coat film transfer tape after use.
2. Description of the Related Art
An example of structure of this kind of coat film transfer tool is shown in FIG. 21, and in this transfer tool, in a case (a) that can be held and manipulated by a single hand, a feed reel (c) with a coat film transfer tape (b) wound thereabout and a take-up reel (d) for collecting the coat film transfer tape (bxe2x80x2) after use are rotatably provided, and a coat film transfer head (f) for pressing the coat film transfer tape (b) onto the object of transfer is protruding at the front end of the case (a). The both reels (c) and (d) are wound up automatically as being linked by an interlock mechanism. (g) so as to cooperate with each other. In this interlock mechanism (g), gears (h) and (i) provided on the outer circumference of the both reels (c) and (d) are engaged with each other.
When this coat film transfer tool is used as an erasing tool for correcting a wrong letter or the like, the case (a) is held by one hand, and moved in a desired direction while pressing the coat film transfer tape (b) tightly to the correction area (the object of transfer) by a pressing portion (j) of the head (f). As a result, the corrective paint layer of the coat film transfer tape (b) in the pressing portion (j) of the head (f) is applied on the correction area, and the letter is deleted, and the coat film transfer tape (bxe2x80x2) after use is automatically wound up and collected by the take-up reel (d).
In this case, as being used, the outer diameter of the coat film transfer tape (b) on the feed reel (c) becomes smaller, while the outer diameter of the coat film transfer tape (bxe2x80x2) on the take-up reel (d) becomes larger. On the other hand, the rotation ratio of the feed reel (c) and take-up reel (d) (corresponding to the gear ratio of the interlock mechanism (g)) is always constant. Accordingly, the take-up speed of the take-up reel (d) tends to be faster gradually as compared with the feed speed of the feed reel (c), and to prevent thls, therefore, it is necessary to synchronize the feed speed and take-up speed. For this purpose, the feed reel (c) is provided with a clutch mechanism (k) for synchronizing the feed speed and take-up speed.
That is, in the feed reel (c), a boss (m) of a drive gear (h) rotatably supported on a support shaft (n), and a tape feed core (o) with the coat film transfer tape (b) wound thereabout is rotatably fitted on the boss (m), and the clutch mechanism (k) is provided between the boss (m) and the tape feed core (o).
In this clutch mechanism (k), elastically deforming clutch pawls (p), (p) provided on the outer circumference of the boss (m) are engaged with multiple stopping portions (q), (q), . . . provided in the inner circumference of the tape feed core (o), elastically.
As the take-up speed is gradually increased as compared with the feed speed, and the synchronism of the two speeds is broken to increase the torque acting on the tape feed core (o), the clutch mechanism (k) causes the tape feed core (o) to slide and rotate on the boss (m), so that the feed speed is synchronized with the take-up speed.
In such clutch mechanism (k), the engaging and disengaging action of the clutch pawls (p), (p) and stopping portions (q), (q), . . . is intermittently repeated elastically with a clicking sound, the manipulating hand of the user may feel discomfort, and running of the coat film transfer tape (b) may be uneven, and as the use is continued further, the engaging and disengaging action becomes more frequent as the revolution speed of the tape feed core (o) increases, and the discomfort and uneven running become more obvious, and further improvements were demanded.
Concerning this point, the present inventors already proposed a clutch mechanism (r) as shown in FIG. 22 (see, for example, Japanese Laid-open Patent No. 5-58097). In this clutch mechanism (r), a circular elastic friction member (s) such as O-ring is interposed between the cylindrical outer circumference of the boss (m) and the cylindrical inner circumference of the tape feed core (o) in a frictionally engaged state.
According to this clutch mechanism (r), in the synchronizing action, the three members (m), (s), and (o) relatively slide smoothly, and hence the discomfort and uneven running due to such elastic and intermittent repeating action have been eliminated.
In the structure of this clutch mechanism (r), however, since the transmission of power is to make use of the frictional force by radial load among the three members (m), (s), and (o), the design and manufacture conditions of the friction member (s) are very strict, and it is hard to manufacture, which was a bottleneck for reducing the manufacturing cost.
That is, if the frictional force is too strong, the sense of manipulation tends to be too heavy in the later phase of use. On the other hand, if the frictional force is too weak, the sense of manipulation tends to be too light in the initial phase of use. Hence, considering their relation, the frictional force must be set at an optimum value.
To obtain the optimum value of frictional force, therefore, in design and manufacture of the friction member (s), it is required to match its inner diameter and outer diameter respectively with the cylindrical outer diameter of the boss (m) and the cylindrical inner diameter of the tape feed core (o), but since the friction member (s) itself is also elastic, its thickness in the radial direction or its sectional diameter must be also taken into consideration. It hence requires an additional process for fine adjustment of the shape and dimensions of the friction member (s) after assembling the clutch mechanism (r).
Still more, since the radial dimensions and other conditions of the friction member (s) are set strictly to assemble the friction member (s) between the cylindrical outer circumference of the boss (m) and the cylindrical inner circumference of the tape feed core (o), it was needed to put in by force, and the assembling work was difficult.
It is hence a primary object of the invention to present a novel clutch mechanism of a coat film transfer tool solving the problems in the prior art.
It is other object of the invention to present a clutch mechanism having an inexpensive structure easy to manufacture, by making use of a frictional force by thrust load, in a coat film transfer tool of automatic winding type.
It is other object of the invention to present a coat film transfer tool of automatic winding type comprising such clutch mechanism.
The clutch mechanism of the invention is used in a coat film transfer tool of automatic winding type comprising a feed reel with a coat film transfer tape wound thereabout and a take-up reel for collecting the coat film transfer tape after use, rotatably provided in a case that can be held and manipulated by one hand, in which the take-up reel cooperates with the feed reel, for synchronizing the feed speed and take-up speed of the coat film transfer tape in both reels, wherein power transmission means between a tape winding portion for winding up the coat film transfer tape and a rotary drive unit for rotating and driving this tape winding portion is composed in at least one of the two reels, and power transmission of the power transmission means makes use of the frictional force by the thrust load between the tape winding portion and the rotary drive unit, and is connected and disconnected by the difference in torque between these two members.
The coat film transfer tool of the invention comprises a case having shape and dimensions to be held and manipulated by one hand, a feed reel rotatably provided in the case and winding a coat film transfer tape, a take-up reel rotatably provided in the case for collecting the coat film transfer tape after use, an interlock mechanism for linking these two reels so as to cooperate with each other, and a coat film transfer head protruding at the front end of the case for pressing the coat film transfer tape onto the object of transfer, further comprising said clutch mechanism at least in one of the two reels.
The coat film transfer tool comprising the clutch mechanism is classified into the disposable type to be discarded when the coat film transfer tape is used up, and the refill type that can be used repeatedly only by replacing the spent coat film transfer tape with a new one.
In the coat film transfer tool comprising the clutch mechanism of the invention as power transmission means, the take-up speed of the take-up reel gradually becomes faster as compared with the feed speed of the feed reel, and their synchronism is broken to increase the torque acting on the tape winding portion for winding the coat film transfer tape, and herein the clutch mechanism acts to cause the tape winding portion to slide and rotate on the rotary drive unit to eliminate the torque difference between the two, so that the feed speed is synchronized with the take-up speed.
In this case, the power transmission in the clutch mechanism makes use of the frictional force by thrust load between the tape winding portion and the rotary drive unit, and therefore the structual components relatively slide smoothly in this synchronizing action.
In the structure of the clutch mechanism, by properly adjusting the dimensional relation in the thrust direction between the mutual structual components, the frictional force can be set at an optimum value.
These and other objects and features of the invention will be better appreciated by reading the detailed description based on the accompanying drawings and novel facts indicated in the claims.